I have a hard drive with 4 partitions from a dead PC that I put into an external case to use as a external drive. It is a 500gb drive and it came with a HCL laptop. Initially disk management was showing it to be invalid dynamic disk so after searching all over the internet, i found this link to convert it into a basic drive. Although i was able to get access to two of my partitions but another two are still inaccessible and are not shown in my computer.
I am now using a windows 8 laptop.
I think you may loss the drive letter of that two partitions. You can go to disk management to assign another drive letter to it. In disk management right click the partition that loss drive letter and select change drive letter, in the pop up window select "change"...